I love going down on my boyfriend while he's sleeping. I love his reaction when he wakes up, it's adorable. I've definitely had it go wrong on me before though (which was hilarious.)
I went down on him one night while he was asleep and apparently having a nightmare. He yelled something, sleep-punched me in the head, and put his dick away. It had to have been the strangest, funniest things I've ever seen/ had happen to me. I was on the floor laughing.